Cation distribution in the Bi{sub 4-x}RE{sub x}Ti{sub 3}O{sub 12} (RE = La, Nd) solid solution and Curie temperature dependence

• Published in: Materials characterization Vol. 60; no. 3
• Main Authors: Arreguin-Zavala, J., Villafuerte-Castrejon, M.E., Gonzalez, F., Bucio, L., Novelo-Peralta, O., Sato-Berru, R.Y., Ocotlan-Flores, J.
• Format: Journal Article
• Language: English
• Published: United States 15.03.2009
• Subjects: BISMUTH COMPOUNDS; BISMUTH IONS; CALORIMETRY; CATIONS; COPRECIPITATION; CRYSTALS; CURIE POINT; FERROELECTRIC MATERIALS; LANTHANUM COMPOUNDS; LANTHANUM IONS; LAYERS; MATERIALS SCIENCE; NEODYMIUM COMPOUNDS; NEODYMIUM IONS; ORTHORHOMBIC LATTICES; OXIDES; PEROVSKITE; RAMAN SPECTROSCOPY; SOLID SOLUTIONS; TETRAGONAL LATTICES; TITANIUM COMPOUNDS; X-RAY DIFFRACTION
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2008.09.003

Bi{sub 4-x}RE{sub x}Ti{sub 3}O{sub 12} (RE = La, Nd) ferroelectric powders were prepared by a co-precipitation route. Raman spectroscopy and X-ray diffraction were employed to determine the crystal site of La{sup 3+} and Nd{sup 3+} as well as the effect of their addition on the crystal structure. It was found that La atoms were not only placed preferentially in pseudo-perovskite A sites for concentrations x {<=} 1.2 but also substituted for Bi{sup 3+} in (Bi{sub 2}O{sub 2}){sup 2+} layers for greater concentrations. A similar behavior was observed with the limit value x = 0.8 in case of Nd{sup 3+}. In solid solution La or Nd{sup 3+} ions diminish the distortions in the octahedron formed by oxygen atoms, so there is a tendency to undergo a transition in crystal symmetry from orthorhombic to tetragonal. Finally differential scanning calorimetry (DSC) shows a linear dependence of the Curie temperature (T{sub c}) when the amount of La{sup 3+} or Nd{sup 3+} was increased.